Testing constrained sequential dominance models of neutrinos

Testing constrained sequential dominance models of neutrinos

Constrained sequential dominance (CSD) is a natural framework for implementing the see-saw mechanism of neutrino masses which allows the mixing angles and phases to be accurately predicted in terms of relatively few input parameters. We analyze a class of CSD(n) models where, in the flavour basis, two right-handed neutrinos are dominantly responsible for the 'atmospheric' and 'solar' neutrino masses with Yukawa couplings to $({\nu }_{e},{\nu }_{\mu },{\nu }_{\tau })$ proportional to $(0,1,1)$ and $(1,n,n-2),$ respectively, where n is a positive integer. These coupling patterns may arise in indirect family symmetry models based on A 4. With two right-handed neutrinos, using a χ 2 test, we find a good agreement with data for CSD(3) and CSD(4) where the entire Pontecorvo–Maki–Nakagawa–Sakata mixing matrix is controlled by a single phase η, which takes simple values, leading to accurate predictions for mixing angles and the magnitude of the oscillation phase $| {\delta }_{\mathrm{CP}}| .$ We carefully study the perturbing effect of a third 'decoupled' right-handed neutrino, leading to a bound on the lightest physical neutrino mass ${m}_{1}{\rm{\lesssim }}1$ meV for the viable cases, corresponding to a normal neutrino mass hierarchy. We also discuss a direct link between the oscillation phase ${\delta }_{\mathrm{CP}}$ and leptogenesis in CSD(n) due to the same see-saw phase η appearing in both the neutrino mass matrix and leptogenesis.

hep-ph

Bjorkeroth, Fredrik

afc5f145-d775-4f56-9207-95db839ec02d

King, Stephen F.

f8c616b7-0336-4046-a943-700af83a1538

9 November 2015

Bjorkeroth, Fredrik

afc5f145-d775-4f56-9207-95db839ec02d

King, Stephen F.

f8c616b7-0336-4046-a943-700af83a1538

Bjorkeroth, Fredrik and King, Stephen F.
(2015)
Testing constrained sequential dominance models of neutrinos.
*Journal of Physics G: Nuclear and Particle Physics*, 42 (12), [125002].
(doi:10.1088/0954-3899/42/12/125002).

## Abstract

Constrained sequential dominance (CSD) is a natural framework for implementing the see-saw mechanism of neutrino masses which allows the mixing angles and phases to be accurately predicted in terms of relatively few input parameters. We analyze a class of CSD(n) models where, in the flavour basis, two right-handed neutrinos are dominantly responsible for the 'atmospheric' and 'solar' neutrino masses with Yukawa couplings to $({\nu }_{e},{\nu }_{\mu },{\nu }_{\tau })$ proportional to $(0,1,1)$ and $(1,n,n-2),$ respectively, where n is a positive integer. These coupling patterns may arise in indirect family symmetry models based on A 4. With two right-handed neutrinos, using a χ 2 test, we find a good agreement with data for CSD(3) and CSD(4) where the entire Pontecorvo–Maki–Nakagawa–Sakata mixing matrix is controlled by a single phase η, which takes simple values, leading to accurate predictions for mixing angles and the magnitude of the oscillation phase $| {\delta }_{\mathrm{CP}}| .$ We carefully study the perturbing effect of a third 'decoupled' right-handed neutrino, leading to a bound on the lightest physical neutrino mass ${m}_{1}{\rm{\lesssim }}1$ meV for the viable cases, corresponding to a normal neutrino mass hierarchy. We also discuss a direct link between the oscillation phase ${\delta }_{\mathrm{CP}}$ and leptogenesis in CSD(n) due to the same see-saw phase η appearing in both the neutrino mass matrix and leptogenesis.

Other

** pdf
- Accepted Manuscript**
## More information

Accepted/In Press date: 9 October 2015

Published date: 9 November 2015

Additional Information:
34 pages, 15 figures. Version to be published in J.Phys G. Note the change in title. Clarifying comments added. Previous versions: 32 pages, 15 figures. Improved discussion of chi squared analysis, new plots added. // 29 pages, 13 figures. Minor changes and discussion about the origin of the vacuum alignments added to an Appendix

Keywords:
hep-ph

Organisations:
Theory Group, Physics & Astronomy

## Identifiers

Local EPrints ID: 410453

URI: http://eprints.soton.ac.uk/id/eprint/410453

PURE UUID: 64917b30-709d-4a33-a0a3-f5c9a7780880

## Catalogue record

Date deposited: 08 Jun 2017 16:31

Last modified: 11 Nov 2019 19:02

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## Contributors

Author:
Fredrik Bjorkeroth

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